transmutation of elements, conversion of one chemical element into another. The expression has both historical and contemporary significance. The transmutation of certain metals into gold by means of a substance called the philosopher's stone was one of the two most ambitious quests of the alchemists (see alchemy); the other was for the elixir of life that would cure all diseases, restore youth to the aged, and make youthfulness eternal. The possibility of finding the philosopher's stone harmonized with ideas long generally held, and honest and able persons once hoped to find it. Now and then a charlatan professed to have found it.
In modern times it has been found that a transmutation from one element to another actually does occur in the process of natural radioactivity. Transmutation of elements can be achieved artificially by the bombardment of elements with high-speed particles or ions using a particle accelerator. Both artificial and natural transmutations involve changing the number of protons in the atomic nucleus. The transuranium elements are created in this manner. When a nucleus is bombarded with neutrons from an atomic pile or nuclear reactor, some of the neutrons will be absorbed, resulting in an unstable nucleus. The nucleus then becomes more stable by converting one of its neutrons into a proton by beta decay, becoming a nucleus of the next heavier element in the process.